Hi,
You can see on 'onepage.blade.php' file (Shop->src->Resources->views->checkout), in this files, a component name as 'checkout is created', in this components' created method, you can this a code like -
if(! customerAddress) {
this.new_shipping_address = true;
this.new_billing_address = true;
}
turn it to false.
then see 'customer-info.blade.php (Shop->src->Resources->views->checkout->onepage)
in this file. search for v-if="!this.new_billing_address" and give login button.
Thanks